There has been known lash adjusters for automatically nullifying or adjusting to substantial zero the valve clearance between the intake/exhaust valves and the cylinder heads of an internal combustion engine. These lash adjusters can be classified into two categories: those that utilize externally supplied oil and those that utilize a liquid such as oil pre-charged in the plunger.
A known sealed lash adjuster is disclosed in, for example, a patent document listed below.
This sealed lash adjuster includes a plunger having an lower open end and inserted in a cylindrical body having a bottom and an upper open end such that a reservoir formed in the plunger is communicated with a high-pressure chamber provided below the plunger via a check valve provided at the lower end of the plunger. An oil recycling hole for returning the oil from the high-pressure chamber to the reservoir is formed in the side wall of the plunger. In order to prevent engine oil from flowing into the lash adjuster, the lash adjuster is provided with seal means in the form of two seal members installed at two axial locations between the open end of the body and the oil recycling hole, and between the slidable portions of the plunger and body in contact with each other. The lash adjuster is charged with a predetermined amount of oil supplied through an oil injection port formed in the top end of the plunger.
The two seal members, that is, a first seal member provided on the slidable portion of the plunger and a second seal member provided on the slidable portion of the body, are arranged at the two axial locations such that the space between the first and second seal members is expanded when the plunger is pushed into the body, but contracted when the plunger is projected from the body.
In assembling the sealed lash adjuster, the plunger provided with the first seal member is inserted into the body provided with the first seal member, to a predetermined depth where the first seal member of the plunger has passed the second seal member installed on the body.